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      <details id="toc" open><summary>Table of contents</summary><ul>
<li><span class="stability_3"><a href="#querystring_query_string">Query string</a></span>
<ul>
<li><a href="#querystring_querystring_decode"><code>querystring.decode()</code></a></li>
<li><a href="#querystring_querystring_encode"><code>querystring.encode()</code></a></li>
<li><a href="#querystring_querystring_escape_str"><code>querystring.escape(str)</code></a></li>
<li><a href="#querystring_querystring_parse_str_sep_eq_options"><code>querystring.parse(str[, sep[, eq[, options]]])</code></a></li>
<li><a href="#querystring_querystring_stringify_obj_sep_eq_options"><code>querystring.stringify(obj[, sep[, eq[, options]]])</code></a></li>
<li><a href="#querystring_querystring_unescape_str"><code>querystring.unescape(str)</code></a></li>
</ul>
</li>
</ul></details>

      <div id="apicontent">
        <h2>Query string<span><a class="mark" href="#querystring_query_string" id="querystring_query_string">#</a></span></h2>

<p></p><div class="api_stability api_stability_3"><a href="documentation.html#documentation_stability_index">Stability: 3</a> - Legacy</div><p></p>

<p><strong>Source Code:</strong> <a href="https://github.com/nodejs/node/blob/v14.19.1/lib/querystring.js">lib/querystring.js</a></p>
<p>The <code>querystring</code> module provides utilities for parsing and formatting URL
query strings. It can be accessed using:</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> querystring = <span class="hljs-built_in">require</span>(<span class="hljs-string">'querystring'</span>);</code></pre>
<p>The <code>querystring</code> API is considered Legacy. While it is still maintained,
new code should use the <a href="url.html#url_class_urlsearchparams" class="type">&#x3C;URLSearchParams></a> API instead.</p>
<section><h3><code>querystring.decode()</code><span><a class="mark" href="#querystring_querystring_decode" id="querystring_querystring_decode">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.99</span>
</div>
<p>The <code>querystring.decode()</code> function is an alias for <code>querystring.parse()</code>.</p>
</section><section><h3><code>querystring.encode()</code><span><a class="mark" href="#querystring_querystring_encode" id="querystring_querystring_encode">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.99</span>
</div>
<p>The <code>querystring.encode()</code> function is an alias for <code>querystring.stringify()</code>.</p>
</section><section><h3><code>querystring.escape(str)</code><span><a class="mark" href="#querystring_querystring_escape_str" id="querystring_querystring_escape_str">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.25</span>
</div>
<ul>
<li><code>str</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>The <code>querystring.escape()</code> method performs URL percent-encoding on the given
<code>str</code> in a manner that is optimized for the specific requirements of URL
query strings.</p>
<p>The <code>querystring.escape()</code> method is used by <code>querystring.stringify()</code> and is
generally not expected to be used directly. It is exported primarily to allow
application code to provide a replacement percent-encoding implementation if
necessary by assigning <code>querystring.escape</code> to an alternative function.</p>
</section><section><h3><code>querystring.parse(str[, sep[, eq[, options]]])</code><span><a class="mark" href="#querystring_querystring_parse_str_sep_eq_options" id="querystring_querystring_parse_str_sep_eq_options">#</a></span></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v8.0.0</td>
<td><p>Multiple empty entries are now parsed correctly (e.g. <code>&#x26;=&#x26;=</code>).</p></td></tr>
<tr><td>v6.0.0</td>
<td><p>The returned object no longer inherits from <code>Object.prototype</code>.</p></td></tr>
<tr><td>v6.0.0, v4.2.4</td>
<td><p>The <code>eq</code> parameter may now have a length of more than <code>1</code>.</p></td></tr>
<tr><td>v0.1.25</td>
<td><p><span>Added in: v0.1.25</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>str</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The URL query string to parse</li>
<li><code>sep</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The substring used to delimit key and value pairs in the
query string. <strong>Default:</strong> <code>'&#x26;'</code>.</li>
<li><code>eq</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a>. The substring used to delimit keys and values in the
query string. <strong>Default:</strong> <code>'='</code>.</li>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a>
<ul>
<li><code>decodeURIComponent</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> The function to use when decoding
percent-encoded characters in the query string. <strong>Default:</strong>
<code>querystring.unescape()</code>.</li>
<li><code>maxKeys</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> Specifies the maximum number of keys to parse.
Specify <code>0</code> to remove key counting limitations. <strong>Default:</strong> <code>1000</code>.</li>
</ul>
</li>
</ul>
<p>The <code>querystring.parse()</code> method parses a URL query string (<code>str</code>) into a
collection of key and value pairs.</p>
<p>For example, the query string <code>'foo=bar&#x26;abc=xyz&#x26;abc=123'</code> is parsed into:</p>
<!-- eslint-skip -->
<pre><code class="language-js">{
  <span class="hljs-attr">foo</span>: <span class="hljs-string">'bar'</span>,
  <span class="hljs-attr">abc</span>: [<span class="hljs-string">'xyz'</span>, <span class="hljs-string">'123'</span>]
}</code></pre>
<p>The object returned by the <code>querystring.parse()</code> method <em>does not</em>
prototypically inherit from the JavaScript <code>Object</code>. This means that typical
<code>Object</code> methods such as <code>obj.toString()</code>, <code>obj.hasOwnProperty()</code>, and others
are not defined and <em>will not work</em>.</p>
<p>By default, percent-encoded characters within the query string will be assumed
to use UTF-8 encoding. If an alternative character encoding is used, then an
alternative <code>decodeURIComponent</code> option will need to be specified:</p>
<pre><code class="language-js"><span class="hljs-comment">// Assuming gbkDecodeURIComponent function already exists...</span>

querystring.<span class="hljs-title function_">parse</span>(<span class="hljs-string">'w=%D6%D0%CE%C4&#x26;foo=bar'</span>, <span class="hljs-literal">null</span>, <span class="hljs-literal">null</span>,
                  { <span class="hljs-attr">decodeURIComponent</span>: gbkDecodeURIComponent });</code></pre>
</section><section><h3><code>querystring.stringify(obj[, sep[, eq[, options]]])</code><span><a class="mark" href="#querystring_querystring_stringify_obj_sep_eq_options" id="querystring_querystring_stringify_obj_sep_eq_options">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.25</span>
</div>
<ul>
<li><code>obj</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> The object to serialize into a URL query string</li>
<li><code>sep</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The substring used to delimit key and value pairs in the
query string. <strong>Default:</strong> <code>'&#x26;'</code>.</li>
<li><code>eq</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a>. The substring used to delimit keys and values in the
query string. <strong>Default:</strong> <code>'='</code>.</li>
<li><code>options</code>
<ul>
<li><code>encodeURIComponent</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> The function to use when converting
URL-unsafe characters to percent-encoding in the query string. <strong>Default:</strong>
<code>querystring.escape()</code>.</li>
</ul>
</li>
</ul>
<p>The <code>querystring.stringify()</code> method produces a URL query string from a
given <code>obj</code> by iterating through the object's "own properties".</p>
<p>It serializes the following types of values passed in <code>obj</code>:
<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt" class="type">&#x3C;bigint></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string[]></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number[]></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt" class="type">&#x3C;bigint[]></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean[]></a>
The numeric values must be finite. Any other input values will be coerced to
empty strings.</p>
<pre><code class="language-js">querystring.<span class="hljs-title function_">stringify</span>({ <span class="hljs-attr">foo</span>: <span class="hljs-string">'bar'</span>, <span class="hljs-attr">baz</span>: [<span class="hljs-string">'qux'</span>, <span class="hljs-string">'quux'</span>], <span class="hljs-attr">corge</span>: <span class="hljs-string">''</span> });
<span class="hljs-comment">// Returns 'foo=bar&#x26;baz=qux&#x26;baz=quux&#x26;corge='</span>

querystring.<span class="hljs-title function_">stringify</span>({ <span class="hljs-attr">foo</span>: <span class="hljs-string">'bar'</span>, <span class="hljs-attr">baz</span>: <span class="hljs-string">'qux'</span> }, <span class="hljs-string">';'</span>, <span class="hljs-string">':'</span>);
<span class="hljs-comment">// Returns 'foo:bar;baz:qux'</span></code></pre>
<p>By default, characters requiring percent-encoding within the query string will
be encoded as UTF-8. If an alternative encoding is required, then an alternative
<code>encodeURIComponent</code> option will need to be specified:</p>
<pre><code class="language-js"><span class="hljs-comment">// Assuming gbkEncodeURIComponent function already exists,</span>

querystring.<span class="hljs-title function_">stringify</span>({ <span class="hljs-attr">w</span>: <span class="hljs-string">'中文'</span>, <span class="hljs-attr">foo</span>: <span class="hljs-string">'bar'</span> }, <span class="hljs-literal">null</span>, <span class="hljs-literal">null</span>,
                      { <span class="hljs-attr">encodeURIComponent</span>: gbkEncodeURIComponent });</code></pre>
</section><section><h3><code>querystring.unescape(str)</code><span><a class="mark" href="#querystring_querystring_unescape_str" id="querystring_querystring_unescape_str">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.25</span>
</div>
<ul>
<li><code>str</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>The <code>querystring.unescape()</code> method performs decoding of URL percent-encoded
characters on the given <code>str</code>.</p>
<p>The <code>querystring.unescape()</code> method is used by <code>querystring.parse()</code> and is
generally not expected to be used directly. It is exported primarily to allow
application code to provide a replacement decoding implementation if
necessary by assigning <code>querystring.unescape</code> to an alternative function.</p>
<p>By default, the <code>querystring.unescape()</code> method will attempt to use the
JavaScript built-in <code>decodeURIComponent()</code> method to decode. If that fails,
a safer equivalent that does not throw on malformed URLs will be used.</p></section>
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